


My personal trainer

by ctric_acid



Category: Original Work
Genre: Alpha/Beta/Omega Dynamics, Alpha/Omega, Angst, Awkward Crush, Consent, Developing Relationship, Falling In Love, Fluff, Fluff and Angst, Gay, Happy Ending, Implied/Referenced Dubious Consent, Implied/Referenced Underage Relationship(s), Introspection, M/M, Opposites Attract, Other Additional Tags to Be Added, Overweight, Rating May Change, Romance, Self-Esteem Issues, Slow Build, Soulmates, Training, True Mates, Weight Issues
Language: English
Status: In-Progress
Published: 2019-09-17
Updated: 2019-09-25
Packaged: 2020-10-20 12:23:51
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 5,000
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20675348
Author URL: https://archiveofourown.org/users/ctric_acid/pseuds/ctric_acid
Summary: Theo isn't thin and petite like other omegas: 80 pounds are keeping him away from the beauty ideal of his secondary gender. He decided to join the local gym, but his efforts don't seem to bring him anywhere near his weight loss goal.That is, until Keith, an alpha who's a regular at their gym, notices his struggles and decides to take him under his wing.But there seems to be more to him than meets the eye.





	1. Chapter 1

**Author's Note:**

> Hi! This is my first work >///<
> 
> I wanted to make a character who's overweight, since I don't see many around, especially in the BL genre, and weight struggles are a topic close to my heart.
> 
> As you can see from the tags this is set in an ABO/soulmates universe, but I gotta warn you that my take on the genres is going to be a bit more cynical than usual. But don't worry, there will be plenty of fluff to make up for it!
> 
> Thanks for coming and enjoy ❤️

No one was watching, but Theo felt as if all the eyes in the room were on him.

He tried to suppress the little noises that came out of his mouth between shallow breaths, even if he knew that it was pointless, a bit silly. After all, anyone could tell how weak and untrained he was just by looking at him.

He stepped down from the threadmill, panting. The cute omega girl on the exercise bike a few feet away waved at him and smiled. He tried his best to do the same and return the greeting. They were barely acquaintances, but she was sweet and treated him with kindness. Theo was grateful for moments like these, when she tried to cheer him up. He appreciated it probably more than she imagined.

He sat on a bench and his eyes went to his thighs. He noticed they were about three times bigger than the girl's. Seeing how that observation made him feel, he wished his brain never came up with the thought in the first place.

A gentle breeze came from an open window and it felt good on his damp skin. Outside, a lone cherry tree was in full bloom. Theo spent a few moments appreciating the contrast of its pink flowers against the late morning sky. It reminded him of that one time he went to Japan as a kid, to visit his grandparents. It was full of pink trees, just like that.

He grabbed his refillable bottle and took a few sips. Normally he could run for 20, sometimes even 30 minutes, but he barely reached the 10 minute mark. He wasn't exhausted yet, but perhaps he was simply not in a good mood for a gym session. Would he ever get used to it? Maybe he should work out more, make it even more of a habit. That might have been why so many people seemed to like it. Would Theo ever learn to enjoy going through _that_ more than once a week?

Well...

Maybe it wasn't a matter of enjoyment. He hadn't lost much weight since he started exercising over five months earlier, so maybe he should do more. But the idea of increasing his workout sessions still didn't exactly fill him with excitement.

He moved back short strands of dark brown hair stuck to his forehead, as he let his eyes wander around the gym. At that time of the day it was relatively empty, which was nice, but he could still recognize some of the regulars. Like the nice girl. Or the two beta women who were chatting together every single time he saw them. There was also a beta guy he distantly remembered seeing in his maths class back in high school, but Theo was too shy to approach him and catch up. He had seen a few times a middle-aged man, it wasn't clear if he was an alpha or a beta, but he attracted a lot of attention with his chatty attitude and huge, ripped torso covered in tattoos. Then there was an alpha guy. Theo saw him almost every time he went to the gym. He wasn't the bulkiest in the room, but his body was definitely impressive. 

The guy was currently doing some kind of weight training. He looked like he was in his early 20s, just like Theo, but perhaps slightly older. The smaller man watched from a distance his workout, which seemed way too difficult for himself. The alpha's defined muscles contacted with each movement, as he lifted his arms, a weight on each side, his olive skin glimmering with sweat. Oddly enough, Theo was relieved to see that he wasn't the only sweaty one. Except the alpha looked hot, while Theo was just a gross mess who got his shirt drenched after barely 5 minutes of running.

The alpha's icy blue eyes met Theo's hazel ones for a split second. The omega immediately looked away, bringing the bottle to his lips in an attempt to fake indifference.

Wow, he was caught staring. So, so embarrassing.

He wanted to believe that the man didn't notice him, or that he wasn't too mad or disgusted at him. That glare was intimidating, though, and didn't leave much room for hope. Quickly, he flung his eyes back to the alpha and saw that he wasn't looking at him anymore. In fact, he was back to minding his own business and didn't seem to care. But Theo still felt a sting of pain in his chest.

He knew comparing himself to other people would just make him feel worse, but sometimes he couldn't help it. 

No omega ever got as fat as him. Apparently there was some kind of mysterious biological magic that made them naturally prettier, healthier. Scientists were still trying to figure out what was behind the "breeding" gender. The term had something revolting about it and it made Theo cringe when people used it. But despite the horrible things he heard, and how fellow omegas always talked about their gender as a social curse, he felt bad for not being gifted with that natural beauty, and he couldn't stand it when people assumed he was a short beta because of his size. 

He got up and decided to work out some more. His eyes landed on a machine that, as far as he could tell, was used to exercise legs. It worked by pushing a panel connected to a weight. To be fair, he usually stuck to running, since he didn't want to make a fool of himself by using equipment he had no knowledge of, but he had seen people use that machine and it didn't seem too complicated. So he hopped on the seat.

It was hard.

He couldn't wrap his mind around how anyone could do this so effortlessly, while he had to summon all his mental and physical strength only to move the panel a few inches back, not even close to stretching his legs out completely as he was supposed to. He tried again, as he held onto the seat with his hands, while uncomfortably pushing his back against the backrest. 

It was too much, and soon he stopped. 

He groaned in frustration, as he looked at his feet, placed on the unmoving panel. His thighs were pushed against his soft, round belly. Maybe it wasn't the best day to work out, after all. His mind went to the things he wanted to do in the afternoon: he had promised Itsuki he would make gyoza for dinner, but since all the family would be there he thought he could also make something nice using the strawberries he grew in their garden. 

He liked cooking for his family, but thinking about food while giving up on exercising only made him feel like a bigger loser.

That was when he felt it.

A presence at his side. And a _scent_.

The alpha was standing a few feet away from the machine, staring. Theo blinked a few times. He felt like a trapped animal. What was the guy doing? Did he want to use the machine? But why was he looking at him like that?

As surprised as the alpha's presence made him, there was something else that shocked him more.

Not taking scent blocking pills was considered inappropriate for alphas and omegas in public places. Was the guy a pervert? Well, it was possible, but Theo didn't want to run to conclusions so easily. There was something off. His scent was very, very faint, not nearly as potent as what his family members smelled like during the rare times he had seen them when they were off their pills, at home. He didn't know people could emit that kind of scent. Weird. Was he sick? Were his pills not working properly or something?

He smelled great, though.

"Get off".

The sudden command came with an aloof and uncaring tone. Being a bit frightened by the bigger man, Theo did as he was told, but soon he felt a sting of annoyance directed at the guy, who just went ahead and started pulling some levers near the seat. He really didn't have to be so rude and intimidating about it, if he wanted to use the machine. It was true that Theo had been sitting on it for a while and he wasn't going to use it anymore, but he could have asked!

He was about to get his water bottle and leave, when the other man stepped away from the gym equipment. He stared at Theo. And Theo stared back in confusion. 

"Try it now".

Oh. Oh?

The omega carefully sat on the machine, still skeptical, untill he found that his back had better support. It felt more comfortable. The alpha was still watching him, his cold expression contrasting with the heavenly scent in the air. Was he helping him? He was, wasn't he?

Theo tried to ignore his intimidating presence and lifted both his legs to put his feet on the panel. When he pushed he found that it was a lot easier to lift the weight. The omega felt a bit stupid for not realizing that the machine was customizable: of course there were settings he could adjust! He was still grateful to have found out, even if it was embarrassing that the man had witnessed his incompetence. He pushed a few more times, managing to stretch his legs against the weighted panel, happy to see that the motion was a lot more bearable.

The alpha suddenly grabbed his left ankle and calf from below, which made Theo jump on his seat. The other man looked at him, unfazed by the omega's surprise, as he gave a small push upwards to let him know that he wanted him to move his legs. So Theo let him readjust his position.

"Your legs should be at a right angle and your toes have to reach past your knees, like this. Otherwise it'll be too much strain for your knees and you'll hurt yourself".

The smaller man nodded as he took note of the information in his mind. The guy seemed kind, but wasn't this situation a bit weird? Or was it all perfectly normal, except the scent had gotten to Theo's brain, and he was too intoxicated to stay completely indifferent as big, rough hands grabbed him and moved him so firmly, yet so gently?

Whatever it was, the guy was helping him and the omega still felt a bit bad for assuming the alpha to be a jerk at first.

"Thank you".

His voice came out weaker than intended, and he gave the bigger man a tentative smile. Something about the way the alpha broke eye contact spoke of awkwardness and shyness, rather than the arrogance he had assumed the man possessed.

The workout resumed. The alpha was still watching him and the odd atmosphere never completely faded, but Theo tried to ignore his presence and focused on the exercise. The taller man broke the silence a few times to give Theo some tips, but didn't intervene otherwise.

The weight got heavier and heavier against his feet, and after a while it was too much for Theo to handle, so he stopped. He was panting heavily, his face on fire. Not only his legs were about to give in, as he would have expected, but his abdomen felt tremendously tired too.

"Do a couple more".

Theo gave him a wide-eyed look and shook his head with a whine. The alpha crossed his arms and raised an eyebrow. Was he mocking him? Did he enjoy his suffering? But then, unexpectedly, the taller man's expression softened, slightly but noticeably.

"You're almost there, you're doing great. Just two more. I know you can do it".

Theo was too exhausted and confused to realize that those few words were all it took for him to summon the last of his strength to push the panel for two more times, if only to focus on the pain and avoid dealing with the way the oddly endearing encouragement made his chest tighten. 

He collapsed on the seat in agony, open-mouthedly grasping for air, eyes shut.

"You did a great job".

Theo smelled it before he saw it, or even felt it on his shoulder. He snapped his eyes open and looked up at the other man, who was giving him a friendly pat, and the omega could have sworn that on his handsome face there was a hint of a smile.

What was even that?

Theo didn't really know what to do, so he looked away, trying to compose himself. This guy was a bit weird, but he was nice and smelled too good. It didn't help that he had the alpha's wrist gland so close to his face. Even up close the smell wasn't very powerful, but damn, it was the best scent the omega ever felt. 

It was an earthy fragrance, and it reminded him of rainy days, of familiar things, like his early morning visits to the garden behind his family house. 

He had to force himself not to shamelessly rub his nose against the alpha's wrist and risk looking like a creep. Again.

The smaller man stood up, wobbling a bit as he carefully positioned his tired feet on the floor. The alpha brought his arms closer to Theo, as if to catch him in case he fell. He looked up at the taller man, and the man looked back down, at least 5 inches in height setting them apart. 

It went better than expected. Theo didn't think he would end up working out this much, but he did, and the satisfaction felt amazing. And the alpha was so nice. The omega didn't get it, but his presence filled him with excitement and warmth, to the point of dizziness.

"What's your name?"  
"Keith".  
"I'm Theo. Well... I appreciated your help, you're a very good personal trainer".

Theo gave him an cheerful smile and Keith responded with a nod and a blank expression, although his stoic attitude was betrayed by a nervous scratching gesture on his right thigh and a sideways glance.

"Uhm. See you around".

Theo replied with a nod, and shortly after the alpha left. The smaller man watched him go back to his weight training. Then, he collected his water bottle and exited the room as fast as he was able to, on wobbly, tired legs. 

His heart was fluttering in his chest, torn within a mixture of different emotions. 

That was nice. Definitely not the workout session he had expected to get. He was glad Keith had pushed him to do more, and had helped him. It was like he was inside a dream, a very nice dream. 

Theo let himself soak into the fluffy feeling, and tried to push out of his mind the faint thought that there was something very, very odd about the way he was starting to like alpha's scent way too much for his own good.


	2. Chapter 2

**Summary for the Chapter:**

> Overthinking stuff and some family time.

Theo could see through the kitchen window his mother Peter. The man was short and always had thick, round glasses framing his face. At that moment he was absently rubbing the back of his shoulder. He looked tired. The late afternoon sun put a warm tint on the white exterior of the house, the same color as Peter's hair.

In front of the kitchen, the backyard was filled with blooming plants, visited by a few bees here and there, collecting the last pollen of the day. Theo loved flowers so there were a lot of them, but he also grew a few aromatic herbs, like rosemary and sage, as well as fruit plants, cherry tomatoes and blueberries being two of them. Most of them weren't ripe yet, although the juicy strawberries had already gone missing a few hours earlier, now inside the cheesecake in the fridge.

The shed in the back of the garden was open and Theo was resting on the wooden bench he had dragged inside the little wooden house from the outside, along with a light blanket and fluffy pillows to make it more comfortable. The sight of the sun-kissed plants was soothing, but could only calm him down so much, when his mind was mudded by the thoughts of what happened earlier in the gym.

He knew clinging to other people's kindness wouldn't bring him any good, and yet, there he was. He must have been with Keith for less than 20 minutes, but he was already harboring a crush on the alpha. The handsome, way out of his league alpha. A part of Theo wanted to forgive himself for feeling that way, because any normal person would have found the man attractive. But another part of him reminded him that he shouldn't even try to get close to him. He had to get rid of this crush, because it would only set him up for ridicule, since there was no way things could work out. After all, there was no reason for them to, so the omega needed to stop deluding himself: the alpha was just kind enough to help. He felt bad for the fat, incompetent guy at the gym, so he had to intervene. That was it.

Theo covered his face with his hands in frustration, his head resting on the inside wall of the shed. As he replayed the scene in his head, he cringed at himself. Maybe he should try to avoid him, change his gym schedule. But what if he met him again, anyway? After all, the man went to the gym a lot. Not going back at all would likely be the safest option, which the omega was seriously considering, despite knowing that a stupid crush was a silly reason to give up on exercising. Even an excuse, perhaps.

The light, muffled sounds of steps on the trail that connected the family house to the shed could only belong to Itsuki. Theo lifted his gaze and saw the omega coming towards him, slender limbs careful not to step on the plants. The man was 35, but like most omegas, he looked younger than that. People often said the two of them had the same eyes, although Theo always felt uneasy when he was compared to him. He didn't even think they looked like each other that much, even putting aside the obvious size difference: Itsuki's eyes were similarly almond-shaped, but a much darker shade than the other omega's hazel ones, and his hair was perfectly straight and black, while Theo's had a slight wave and was lighter. Overall, the older omega looked a lot more Japanese, but his small, upturned nose was just like their mother's. Theo always thought he was really pretty.

Itsuki stopped at the entrance of the shed, his hand resting on the door frame as he gave the younger man a worried look.

"Are you feeling alright?"

Theo knew Itsuki would pick up on his discomfort, but he really didn't want to talk about it.

"I'm just really tired."

It wasn't a lie, but he hoped it wouldn't show on his face that it wasn't the whole truth, either. Relief filled him when he saw a sweet smile forming on the other omega. At the same time, he felt a bit bad for hiding the truth.

"You worked out a lot today, huh?"

Theo nodded and hugged the pillow in his lap, his gaze on the flowers outside, gently tugged by a breeze.

"Our dumbass sister Lyd, Melanie and Little Lizzy will be here soon. I already cut out circles of dough for the gyoza, but I didn't start closing them because you're the only one that doesn't pinch them ugly."

"Oh, right, I lost track of time. Thanks for starting ahead. Just give me a second and I'll make them."

Itsuki nodded and smiled, then started walking back through the garden, while Theo reluctantly got up from the bench and quickly rearranged the pillows on it, before heading inside as well to finish the dumplings as he had promised.

* * *

The living room was filled with noises of cutlery and laughter coming from all the adults at the table, as Little Lizzy reenacted something that happened to her at school. The 6 year-old had a special talent for directing attention to herself, and everyone in the family adored her.

"C'mon Lizzy, be careful. You're spilling food on the table"

Her dad Lydia accompanied the warning with a raised eyebrow and crossed arms, although amusement tinted her expression. The child looked down at her plate and was surprised to see pieces of vegetables on the tablecloth.

"Oh! Sorry..."

As she mumbled the apology she started collecting the veggies with her fork and put them on the edge of her plate. Her mom, Melanie, shifted in her seat to help her daughter get all the pieces of spilled food.

"Oh, don't worry about it, girls" Said Peter, chuckling as he watched his grandchild and daughter in law. Next to him, his alpha wife Yui was similarly amused and delighted, warm smiles on both of their wrinkly faces. Theo's parents had developed a soft spot for their omega daughter in law and the youngest in the family. It was normal to spoil one's own grandchildren, after all. And without a doubt, Lydia and Melanie's second child, which they announced would come in a few months, would receive lots of love from her grandparents as well.

"Uncle Theo, can we have your cake, please?"

Theo's little nephew was looking at him with big eyes, as she shifted impatiently in her seat and played with her long, brown braids, twisting them in her small fingers. The omega smiled at the sight. She was too adorable!

"Of course. But you should eat some more veggies before dessert."

Little Lizzy frowned and Lydia cut in.

"Uncle's right, chipmunk. These carrots are delicious! Granny made them with tons of love!"

At that, Little Lizzy reluctantly agreed to eat the last few carrots in her plate. When everyone was finished, Peter was about to get up to pick up the empty plates, but Itsuki stopped his old mother from forcing himself and collected them instead.

Theo helped as well. When he brought the cheesecake to the table, he got an excited response from the little girl who had been waiting for it the whole evening.

* * *

After an hour past dinner, while the rest of his family was chatting in the living room, Theo took the chance to go outside and water his plants before he forgot to. He put on shoes and went to retrieve the watering can from the shed in the back of the yard.

"Theo!"

As he was filling the watering can, Lydia made her way out of the house and into the garden, grinning. Theo waved at her, unable hide a small smile. Now that the alpha was there, he knew that what could have been a relaxing activity was going to be anything but that. Despite being a respectable university professor and the oldest among them, at 37 years-old, the woman _loved_ being a goof at home. She put an arm across the smaller man's shoulders, tugging him closer. Theo almost lost his balance, his legs being still tired and the watering can being heavy, but Lydia didn't let go, her blonde bleached hair almost in the omega's mouth.

"Little Lizzy is trying some clothes mom and dad got her, so I wanted to catch up with my Little Theo." She gave him a few pats on the arm. "How's it going? Huh, want some help with that?"

The omega turned off the tap and begun walking towards the plants followed by the alpha, huffing and wobbling a bit, but managing to sprinkle water on the plants that needed it.

"Nah, thank you. And I'm fine. You know, same old, same old. How's work?"

"Oh, things are great. Just hosted a pretty important conference across the country."

"That's awesome!" 

"Yeah, but travelling for work is really tiring. And I missed my babes!"

Theo smiled and Lydia smiled back. However, soon enough a layer of mischief painted her expression.

"So... What's keeping my Little Theo's head up in the clouds? Hm? Something is going on, isn't it?"

As usual, Lydia didn't beat around the bush and went straight for what she wanted to know. She stared at him and Theo tried playing cool, even though he knew his face was betraying him.

"Oh, well, I'm just a bit tired. That's all".

The alpha kept staring. Theo gulped. 

"You know, it won't do you any good to bottle things up. And don't even try to deny it because I know you always do it".

The young man shifted uncomfortably. "Well, I won't deny it then..."

The alpha raised an eyebrow. "C'mon, what is it, Theo? Having love troubles, maybe? Or-"

The omega froze. He stayed still for a moment too long, his eyes just a little too wide for the shock that filled him to not be obvious.

And possibly, Lydia looked even more surprised than him. She gasped loudly, bringing a hand next to her mouth.

"Oh my god! I can't believe I got it right! At the first try! Who is-"

"Shhh! Be quiet! I don't want the whole neighborhood to hear about this!"

The woman fixed her voice and made a visible effort to contain herself, but her curiosity still came out shamelessly.

"So, who is it? Someone at work? A client?"

Theo sighed. "I hope your daughter doesn't grow up to be this much of a sucker for gossip".

That sent Lydia into a snort-laughing fit, but of course Theo knew the remark wasn't enough to make her back out.

"You know, Mel told me the same. But anyway! Let's get back to business: is there someone I have to punch?"

The omega looked to the side, embarassed, as he watered another plant. "Yes, me. Because I have an embarrassing crush I have to get rid of".

He told his sister what happened earlier that day in the gym, omitting the parts that involved the weird scent, because he still didn't know what to think of it. As she listened, the alpha looked a bit too thrilled for Theo's liking.

"That sounds really sweet! And he was the one who approached you, so that must mean something."

"It probably means he took pity on me because I didn't understand anything and I was doing the exercise wrong. He told me I would get hurt if I continued doing it like I was." He walked to another section of the garden to water more plants, followed by the alpha.

"But maybe he did it because he cares about your safety. And I think that's a great sign. Alphas naturally want omegas to be safe, especially those they like."

Theo looked down at himself. "But he doesn't even know that I'm an omega. I don't look like one."

Lydia frowned. "Well, you can't be so sure about that if you can't read his mind." Theo appreciated the attempt to comfort him, but it wasn't enough. He knew too well how often people mistook him for a beta.

"And half the alphas I know are married to betas, so him thinking you're one isn't a good enough reason to dismiss the possibility that he might like you. Really, what's important is that he was kind to you. You can't deny that much."

Theo lost himself in thought for a few moments, carefully considering his older sister's words, until she cut in again.

"And besides, there's nothing wrong with having a crush."

The young man felt a sting of embarrassment in his chest. "No way, it's ridiculous. I'm way out of his league!"

"I wouldn't be so sure about that. You're very cute."

Theo furrowed his eyebrows. He wasn't going to reply to _that_.

"Oh c'mon, I'm 100% positive he'd be happy to have you like him!"

He looked up at her. "How can you say that?"

"Well, he seems to be a nice guy, and for nice people it's always flattering to have someone like them. Even if it isn't mutual. Although it might be."

Theo didn't believe the last part. But maybe, what his sister said made sense. _If_ Keith was a good person, after all.

"I guess so."

"See? It's gonna be good."

"You say it like it's easy. But I'm not gonna tell him. Never."

"Oh no, no, of course it isn't. But Theo, it would be a waste to give up without even trying, wouldn't it?"

The omega frowned. "Not if the chances of making it are zero."

"Hey! Stop it! You don't even know him enough to be able to tell! But they're not zero, I'm sure of it. You should believe more in yourself".

"...I don't know."

The older woman sighed, but didn't say anything else. The two of them continued watering the plants, cicadas and distant chatter from inside the house filling the silence, until the water was finished.

"Gimmie, I'll refill it for you."

Theo passed the watering can to Lydia, who went back to the tap. It was dark outside, the sky clear but the moonlight weak. A few more stars than usual could be seen but the warm light from inside the house was what shone the brightest on the garden.

It would have been wonferful if his sister was right. But sadly, believing her would only make everything hurt more when things wouldn't go well. No, Theo couldn't risk it.

But he decided he wouldn't stop going to the gym. Somehow, he'd find a way to deal with his feelings, though he wouldn't let them stop him from becoming the person he wanted to be.

Lydia returned with the watering can half-filled to water the very last section of the backyard. Theo grabbed it from her hands and smiled.

"Thanks."

**Notes for the Chapter:**

> Hi 🌼  
I hope you enjoyed this chapter! Writing dialogue was harder than I expected, I hope I didn't mess it up.  
Feel free to leave a comment if you feel like it!

**Author's Note:**

> If you liked it so far feel free to leave a comment to let me know what you think about it. And if you'd like to be a beta reader for this work hit me up!


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